1. Field of the Invention
The present invention relates to the technical field of image processors and, more particularly, to a system of edge direction detection for comb filter.
2. Description of Related Art
In image processing, the amplitude change or discontinuousness of an image typically indicates that an edge direction detection or an edge enhancement or edge sharping operation is performed on the image for extracting a substantial object from the image.
An edge direction detection algorithm typically uses multiple filters to separate the corresponding frequency bands. However, such a way cannot obtain the desired instinctive output signal, so that using a couple of decisions and setting the weights are required for achieving the expected image quality. Thus, such an edge direction detection algorithm can usually detect a vertical or horizontal edge rather than an oblique edge of a composite signal.
In the US pre-grant publication 2006/0268177, a 2D YC separation device and YC separation system has disclosed, which uses an oblique similarity detector and an oblique comb filter to perform an oblique edge detection on the luma of composite signal, thereby obtaining a composite signal with stronger luma and weaker chroma. However, such a technique is suitable for a monochrome image rather than a color image in which the heavier chroma change can cause a decision mistake.
Therefore, it is desirable to provide a system of edge direction detection for comb filter to mitigate and/or obviate the aforementioned problems.